The EISCAT Scientific Association maintains several facilities for measuring ionspheric parameters. The EISCAT Svalbard Radar (ESR) is located close to Longyearbyen on Svalbard, north of Norway, and consists of two radar dishes: a fixed 42m dish aligned with the local magnetic field, and a steerable 32m dish. EISCAT also runs a tristatic UHF radar system, consisting of two passive receivers in Kiruna (Sweden) and Sodankylä (Finland), with a transmitter located in Tromsø in Norway. The Tromsø site is also home to EISCAT's monostatic VHF system and the ionospheric heater.